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TitleElectrical resistivity structure of the Great Slave Lake shear zone, northwest Canada: implications for tectonic history
AuthorYin, Y; Unsworth, M; Liddell, M; Pana, D; Craven, J A
SourceGeophysical Journal International vol. 199, 2014 p. 178-199, Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 20130465
PublisherOxford University Press (OUP)
Mediapaper; on-line; digital
File formatpdf
ProvinceNunavut; Northwest Territories; Alberta; British Columbia; Saskatchewan
NTS73M; 73N; 73O; 73P/03; 73P/04; 73P/05; 73P/06; 73P/11; 73P/12; 73P/13; 73P/14; 74A/03; 74A/04; 74A/05; 74A/06; 74A/11; 74A/12; 74A/13; 74A/14; 74B; 74C; 74D; 74E; 74F; 74G; 74H/03; 74H/04; 74H/05; 74H/06; 74H/11; 74H/12; 74H/13; 74H/14; 74I/03; 74I/04; 74I/05; 74I/06; 74I/11; 74I/12; 74I/13; 74I/14; 74J; 74K; 74L; 74M; 74N; 74O; 74P/03; 74P/04; 74P/05; 74P/06; 74P/11; 74P/12; 74P/13; 74P/14; 75A/03; 75A/04; 75A/05; 75A/06; 75A/11; 75A/12; 75A/13; 75A/14; 75B; 75C; 75D; 75E; 75F; 75G; 75H/03; 75H/04; 75H/05; 75H/06; 75H/11; 75H/12; 75H/13; 75H/14; 75I/03; 75I/04; 75I/05; 75I/06; 75I/11; 75I/12; 75I/13; 75I/14; 75J; 75K; 75L; 75M; 75N; 75O; 75P/03; 75P/04; 75P/05; 75P/06; 75P/11; 75P/12; 75P/13; 75P/14; 76A/03; 76A/04; 76A/05; 76A/06; 76A/11; 76A/12; 76A/13; 76A/14; 76B; 76C; 73D; 76E; 76F; 76G; 76H/03; 76H/04; 76H/05; 76H/06; 76H/11; 76H/12; 76H/13; 76H/14; 76I/03; 76I/04; 76I/05; 76I/06; 76I/11; 76I/12; 76I/13; 76I/14; 76J; 76K; 76L; 76M; 76N; 76O; 76P/03; 76P/04; 76P/05; 76P/06; 76P/11; 76P/12; 76P/13; 76P/14; 83M; 83N; 83O; 83P; 84; 85; 86; 93P; 94A; 94H; 94I; 94P; 95A; 95H; 95I; 95P; 96A; 96H; 96I; 96P
AreaGreat Bear Lake; Great Slave Lake; Lake Athabasca
Lat/Long WENS-122.0000 -105.0000 68.0000 55.0000
Subjectstectonics; tectonic evolution; tectonic environments; tectonic interpretations; tectonic history; electrical properties; Great Slave Lake shear zone
Illustrationslocation maps; sections
ProgramGEM: Geo-mapping for Energy and Minerals Diamonds
Released2014 08 01
AbstractThree magnetotelluric (MT) profiles in northwestern Canada cross the central and western segments of Great Slave Lake shear zone (GSLsz), a continental scale strike-slip structure active during the Slave-Rae collision in the Proterozoic. Dimensionality analysis indicates that (i) the resistivity structure is approximately 2-D with a geoelectric strike direction close to the dominant geological strike of N45?E and that (ii) electrical anisotropy may be present in the crust beneath the two southernmost profiles. Isotropic and anisotropic 2-D inversion and isotropic 3-D inversions show different resistivity structures on different segments of the shear zone. The GSLsz is imaged as a high resistivity zone (>5000 m) that is at least 20 km wide and extends to a depth of at least 50 km on the northern profile. On the southern two profiles, the resistive zone is confined to the upper crust and pierces an east-dipping crustal conductor. Inversions show that this dipping conductor may be anisotropic, likely caused by conductive materials filling a network of fractures with a preferred spatial orientation. These conductive regions would have been disrupted by strike-slip, ductile deformation on the GSLsz that formed granulite to greenschist facies mylonite belts. The pre-dominantly granulite facies mylonites are resistive and explain why the GSLsz appears as a resistive structure piercing the east-dipping anisotropic layer. The absence of a dipping anisotropic/conductive layer on the northern MT profile, located on the central segment of the GSLsz, is consistent with the lack of subduction at this location as predicted by geological and tectonic models.
Summary(Plain Language Summary, not published)
The paper reports on a magnetotelluric study of the Great Slave Lake shear zone, an important tectonic boundary in the western Canadian shield. Three geophysical transects image the deep structure (down to 50 km) and provide constraints on the geological history. Results are interpreted to reflect a change in tectonic style from early collision of the Slave and Rae plates to later strike-slip motion.

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